Regenerative Medicine Flashcards
(222 cards)
1
Q
Regenerative medicine incorporates the body’s …. with ….. to recreate and rebuild cells, tissues and organs
A
The body’s self-healing methods with foreign biological materials
2
Q
Clinical needs for RM is:
A
organ failure caused by:
injury
disease
ageing
3
Q
Current treatments for organ failure are:
A
Surgical reconstruction. Mechanical devices (pace makers, dialysis). Transplantation (hip replacements)
4
Q
Limitations of surgery:
A
complications such as shock, bleeding, infection, thrombosis, embolism, reaction to anaesthetic
5
Q
Problems of transplants are:
A
donor’s tissue dies, immunosuppressants are required, transplants have limited source, rejection
6
Q
Mechanical device problems are..
A
they do not perform the full function of tissues and they cannot grow with tissues.
7
Q
When building a tissue, …. aspects are considered (5)
A
biological, cellular, genetics, anatomical and chemical
8
Q
Bovine cartilage was first engineered on… What was it used for?
A
a mouse in the shape of a human ear. This was only a cast and used as a scaffold for seeding cells.
9
Q
What was wrong with the ear grown on mouse?
A
Mouse provided nutrients for growth however there was no skin coverage and poor mechanical stability
10
Q
Aims of RM are to provide new solutions for treatment of organ failure which have…
A
minimal immune response
11
Q
building blocks of tissues are:
A
scaffolds/biomaterials.
bioactive molecules.
cells.
12
Q
Which tissues compose the structure of an organ?
A
Epithelial, nerve, connective and muscle - provides support and vasculature
13
Q
Wound healing has 3 stages:
A
Inflammatory
Proliferative
Remodelling
14
Q
What occurs in the inflammation stage.. (3)
A
blood clot forms.
leukocytes clean the wound.
viscosity of blood increases for slower blood flow around the injury.
15
Q
In the proliferative phase of wound healing..(2)
A
Blood vessels re-grow.
New granulation tissue forms from fibroblasts.
16
Q
Remodelling stage of wound healing is the longest and involves..(3)
A
organisation of new tissue.
regenerating epithelium.
formation of scar.
17
Q
After 3 months of wound healing, there is regeneration of …% of original strength
A
70-80%
18
Q
There is regeneration, repair or fibrosis of wounds depending on..
A
severity of the wound
19
Q
Fibrosis is … due to…
A
scar formation due to persistent tissue damage
20
Q
Cells used in RM are:
A
Autologous.
Allogeneic.
Xenogenic
Syngenic/Isogenic
21
Q
Xenogenic cells are from..
A
a different species
22
Q
Syngenic/Isogenic cells are from..
A
a genetically identical individual
23
Q
What type of cells have the potential to induce immune response and transmit disease?
A
Allogeneic and xenogenic
24
Q
Autologous and allogeneic cells can be ES, iPSCs or adult stem cells. These can be…
A
multipotent or pluripotent., with different abilities in reproducibility.
25
Differentiated cells are advantageous as..
they have functionality, unlike ESCs/foetal tissue
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Cells used are cultured in growth medium which replaces the function of... Medium consists of...
Replaces function of blood. Consists of growth factors and nutrients.
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Laminar hoods are used with cell cultures in order to...
keep the environment clean and microbe-free.
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Other factors controlled in cell cultures are:
temperature, humidity and gas exchange
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For biomaterials and cells to interact, what is needed?
Properties of biomaterials for attachment of cells
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Attachment of cells is usually done by ... which provides...(5)
```
The ECM provides:
structural support.
mechanical properties.
bioactive cues.
regulates growth factors.
scaffolds for tissue renewal.
```
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ECM consists of (depending on type of tissue):
fibrous structural proteins - collagen, elastin.
adhesive glycoproteins - fibronectin, laminin.
water hydrated gels - proteoglycans, hyaluronan
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Collagen forms ....% of ECM and has a ... structure.
80-90%. It has a triple helical structure
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Proteoglycans are water hydrated gels and are composed of...
glycosaminoglycan chains linked to a protein core
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Adhesive molecules such as .... have ... sequences which mediate cell attachments.
Fibronectin and Laminin have RGD sequences to mediate cell attachments
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RGD sequences consist of which amino acids?
Arg-Gly-Asp
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Integrins recognise most ECM proteins and help with...
cell attachments and activating signalling pathways.
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GMP ensures that medicinal products are...
consistently produced and controlled to quality standards
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biomaterials are mainly used to..
develop scaffolds
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The first biomaterial was used in..
intraocular lenses (contacts)
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Properties of biomaterials evolved from.. to...
from bioinertness, bioactivity to functional tissue
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Materials MUST be..
biocompatible - have an appropriate host response
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Biocompatibility includes resistance to..(3)
blood clots
bacterial colonisation
allow normal healing processes
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Properties of biomaterials to consider:
physical/mechanical.
chemical.
biological.
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Physical properties of biomaterials are their:
strength, elasticity and architecture
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chemical properties of biomaterials include:
degradability - all products and intermediates need to be non-toxic.
resorption - elimination of byproducts.
water content.
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biological properties of biomaterials are:
interactions with cell and ECM.
| release of bioactive signals.
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A common biomaterial is ... what are its properties?
Polymers are large molecules made of chains or rings of monomers. They have molecular weights of 200,000 Da
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When polymers are dehydrated, they are:
hard and brittle
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Some polymers are hydrophilic and can...
swell up and represent soft tissue/hydrated natural tissues
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What are hydrogels?
cross-linked polymer networks which are insoluble but swell in aqueous medium
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The 3 major classes of biomaterials are:
Natural
Synthetic
Semi-synthetic
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Natural biomaterials can be made of:
Proteins - collagen, gelatin, silk, fibrin, elastic and soybean.
Polysaccharides - chitosan, alginates, hyaluronan and chondroitin sulphate.
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Natural biomaterials can be difficult to...and induce....
Difficult to source.
| Can induce immune response (antigens).
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Synthetic biomaterials are polymers such as:
Polylactic acid (PLA), Polyglycolic acid (PGA), Poly(lacti-co-glycolic) acid (PLGA)
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Synthetic materials have advantages of:
can be tailored to suited needs.
| produced on large scale.
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Synthetic materials have questionable functionality since..
they are based on bio-mimicry
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Semi-synthetic biomaterials are hybrid molecules of...
Bio-active macromolecules on synthetic polymers - (Polyethylene glycol)-fibrinogen (PEG)
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Semi-synthetic materials allow for...
different properties of both natural and synthetic materials.
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PEG is semi-synthetic and has... It can control..
biofunctional domains (RGDs). It can control density, stiffness and biodegradability.
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Different bulk and surface properties are needed of biomaterials in different clinical situations. Contact lenses need to be...
transparent, refractive, hold their shape, allow O2 into the cornea
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Surface properties of biomaterials are modified by..
altering molecules or atoms.
| overcoating existing surfaces with another material - can create texture.
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Material surface affects protein adsorption. This is important since..
cells do not directly interact with the material; they interact with a layer of protein which plasma adheres to.
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Materials which resist protein adsorption/cell adhesion are called..
non-fouling surfaces
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Non-fouling surfaces could be useful for..
inhibiting bacterial colonisation
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cell adhesion occurs through membrane receptors and .... of materials
the RGD domain
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cellular responses to materials vary with..
RGD density of the material
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surfaces can be patterned by:
micrometer-scale chemical patterning
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Scaffolds take the role of ECM providing:
```
structural support.
mechanical properties.
biological cues.
growth factor actions.
reg of proliferation and renewal.
```
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When designing scaffold, what needs to be considered? (6)
```
material science.
scaffold architecture.
scaffold-cell interactions.
up-scaling.
3D models.
nutrient supply.
biodegradability.
```
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Biodegradability is important as it reduces..
number of surgeries
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Porosity if important for..
cell attachment through RGD domains
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Acellular tissue matrices are made by..
de-cellularising normal tissues which leaves behind collagen, fibronectin and GAG fibres.
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acellular matrices are good because..(4)
antigens and cellular components are removed so that new cells can attach to the scaffold.
Reduced immune response.
Exploit 3D structure of ECM in real tissues.
Commercially available.
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If de-cellularisation is not done completely, what can happen? (3)
Endotoxins and bacteria can contaminate the sample - causes scar tissue.
Incorrect cell encapsulation.
Effects cross-linking.
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Acellularisation is checked by...
staining for cells in the matrix
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What has been made by acellularised matrices?
Mitral and aortic valves from pig hearts
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Scaffolds are fabricated by: (5)
```
Porogen leaching.
Phase separation.
Electrospinning.
Additive manufacturing.
3D printing.
```
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porogen leaching mixes ... with polymer gel paste. What is the process?
effervescent salt particles. The gel is moulded then placed in water for the salt to be leached. It is then 'freeze-dried' to create a porous scaffold
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Phase separation mixes ... and ... which undergo separation and freeze-drying to create nanofibrous hybrids.
gelatin and silica
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Electrospinning spins polymer solution by using..
electric fields. Polymer is reeled and collected, and then made into scaffolds
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Additive manufacturing joins materials... Produces..
layer by layer to make 3D models. It produces precise morphologies but can only be done with limited biomaterials.
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3D printing is new and upcoming. It can design organs through... and ... However it is...
MRI scans and digital 3D modelling. It is very damaging to cells
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An example of 3D printing is skeletal muscle. This was done using..
Mouse myoblasts.
PCL pillars for structure and cell alignment.
It was cross-linked with thrombin so it gelated to fibrinogen.
Unwanted material was dissolved.
Matured into functional muscle in rats.
84
small molecules are being used to induce tissue regeneration. Eg..
Corticosteroids, hormones, proteins, oligonucleotides, RNA, DNA and BMPs
85
Biomaterials are made to sequester BMPs by...
physically entrapping rhBMP2 into PEG by mixing before the gelation process.
86
In materials which sequester BMPs, cell adhere and secrete MMPs which...
induce proteolysis so that gels release BMPs, allowing them to diffuse and locally act to signal osteoblast precursors
87
Spider can make .. different types of silk with different...
7 types of silk with different functions and properties such as strength and stretch
88
Silk with kinks due to proline residues allow..
toughness
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Silk has been made into..(2)
silk sheets and nanowires (delivery/scaffolds)
90
Growing cell cultures is cheap and easy, but without mixing causes:
conc. grads. to occur.
| issues with growing.
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Bioreactors are dynamic culture systems which mix cultures, giving rise to...
homogeneous conc. of nutrients, toxins and other components
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Bioreactor roles: (4)
establish spatially uniform cell distrib on 3D scaffolds.
overcome mass transport in 3D constructs.
exposure to physical stimuli.
control pH and O2
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When cells are distributed on 3D scaffolds, they need:
high seeding efficiency.
short inoculation period.
uniform distrib. within the scaffold.
94
If cells are static in 3D culture, cells accumulate..
on the top of the material
95
physical conditioning is using hydrodynamic forces on cells such as...
smooth and skeletal muscle and lung tissue - endothelial cells are normally under stress and muscles have constant tension
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Basic bioreactor requirements: (2)
biocompatibility and sterile containment
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Rotating wall bioreactors keep scaffolds...
in suspension
98
Perfusion bioreactors keep the culture medium... Has been used for..
constantly circulating through the TE construct. Used for heart, lung, liver and pancreas
99
compression bioreactors use ... stimulus to move constructs
mechanical
100
Perfusion bioreactors are good for decellularisation, results in...
retention of organ structure
101
defective heart valves are either..
surgically repaired or replaced (with prosthetics)
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Heart valve cells are exposed to ... and ... in vivo
mechanical stretch and hydrodynamic shear stress
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A Flex-Stretch-Flow bioreactor mimics ... for heart valve tissue. Allows..
mechanical stimulation and perfusion.
| Allows laminar flow and media flow over the scaffold
104
challenges of bioreactors are: (2)
mimicking native cell behaviour.
| scale up - most bioreactors have low volume output
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Skin constitutes for ..% of body mass. Its functions are..
10%. Functions in protection, regulation and sensation.
106
Skin structure has layers:
epidermis, dermis, hypodermis
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The epidermis consists of what cells? It has no...
```
Keratinocytes - tough
Melanocytes - UV
Langerhan's - APCs
Merkel - mechanoR
Has no blood vessels
```
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Dermis is the bulk of the skin. It consists of..(7)
collagen, elastin, glycosaminoglycans.
fibroblasts.
blood vessels, hair follicles, sebaceous and sweat glands.
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Hypodermis is composed of a network of .... It functions as...
adipose cells and collagen - mainly acellular.
| Functions as a thermal insulator, shock absorber and stores fat.
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Contracture of skin is tightening of scars. Caused when the .... layer of ... is perturbed
basal layer of epidermis
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Needs for skin replacement:
Acute trauma
Chronic wounds
Surgery
Genetic disorders - bullous conditions
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Most common reason of skin loss are ... which cause ... wounds
burns - cause rapid and extensive wounds. Damaging of large skin areas can lead to death.
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Skin wounds are typed into:
Epidermal
Superficial partial-thickness
Deep partial-thickness
Full thickness
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Epidermal wounds cause...
redness, minor pain, no scarring
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Superficial partial-thickness wounds affect the.. Wound appearance..
epidermis and superficial parts of the dermis.
Wet and weeping, red blisters.
Painful due to exposure of sensory nerves.
Heal spontaneously.
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Deep partial-thickness involves greater dermal damage. Wound appearance is:
Moist, white/red/pink.
Fewer skin appendages remain.
Scarring more pronounced.
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Full thickness skin wounds have complete destruction of regenerative epithelia. Appear:
dry, leathery and rigid.
| No spontaneous healing.
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Treatment of major skin injuries are:
early excision of dry scab.
wound closure.
skin grafts.
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Skin grafts differ by their thickness:
split thickness and full thickness - amount of dermis
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Skin grafts are usually autologous and skin is...
Taken from a non-injured site with no blood supply.
| Meshed to cover the large wound
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Once a skin graft has been placed, inosculation occurs. This is..
the process of revascularisation
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Skin grafts need to...
adhere to the wound bed with no bleeding, infection or movement.
needs a thin layer of connective tissue
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Allografts are used for... Possibilities of...
temporary prevention of fluid loss and wound contamination.
| Could cause pathogen transmission and immunogenic rejection
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Skin substitutes are needed due to..
limited availability of skin grafts.
pain and scarring form donor site.
further pain inflicted on patient.
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There are no ideal skin substitutes yet. For epidermal substitutes what has been used?
Keratinocytes from skin biopsies. They are expanded in culture and delivered to the wound
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Keratinocytes have been delivered to wounds by..
synthetic silicone delivery.
| Spray suspension
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Combination of epidermal substitutes with .... is needed to achieve full thickness healing
dermal substitutes
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Dermal substitutes are..
acellular.
applied onto a prepared dermis.
Alloderm.
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Full thickness burn is treated by a 2 step process:
first applying dermal substitute, followed by an epidermal cover
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Apligraf is bovine type 1 collagen cultured with...
allogeneic neonatal fibroblasts and keratinocytes. Resembles normal skin structure
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OrCel is cultured allogeneic fibroblasts and keratinocytes from neonatal foreskin. How does it promote healing?
Fibroblasts are seeded into bovine collagen sponge with keratinocytes on top. Cytokines and GFs from the product promote host cell migration and healing.
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Limitations of skin replacement strategies:
Wait 3-12 weeks after a biopsy is taken.
| Currently available substitutes only use 2 cell types - no sweat glands/hair
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Epidermolysis bullosa is..
spontaneous skin blistering which is lethal due to infection, sepsis and skin cancer
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Blistering of skin is the epidermis.. Normally it is..
separating from the dermis repeatedly.
| Normally layers adhere through integrins and laminin
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In epidermolysis bullosa, ... is mutated, causing no dermal-epidermal interaction in basal lamina
Laminin 332 (splice site)
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In one patient of epidermolysis bullosa, autologous graft could not be done because...
not enough skin available.
| skin cells had mutation
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In skin gene/cell therapy, genes were manipulated into autologous fibroblasts by...
retrovirus delivering correct LAMb3 into cells.
| NGS was done to make sure LAMB3 integrated in right place (not in oncogene)
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After LAMB3 corrected cells were transplanted, what was seen?
after 21 months, no blisters, not tumourigenic, laminin 332 expression
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Epithelial tissue has been approached by EB formation from iPS. What was used to enhance hair shaft production?
Wnt3b - approach produced extra appendages of skin - sebaceous glands, fat, errector pili muscles, nerves
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Skin substitutes can also be used in vitro for...
cosmetic testing - l'oreal
disease modelling
drug discovery
141
Other skin disorder substitutes can be used for:
Vitiligo
Psoriasis
Sin cancer
Allergies
142
Corneal disease affects corneal function:
transparency, refractive power and eye protection
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Corneal epithelia has functions of:
prevents fluid loss.
create barrier to pathogens.
respond rapidly to wounds.
144
Corneal stroma is ...% of thickness. It consists of... and provides strength and transparency.
90% of corneal thickness.
| Consists of collagen, proteoglycans, glycoproteins
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Keratocytes in corneal stroma are long, thin flattened cells. What do they do?
synthesise and maintain the ECM of stroma
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Corneal endothelium has functions of:
maintaining stromal hydration - for transparency.
| Has pumps/channels to allow solutes and nutrients from the aqueous humor through.
147
Corneal innervation is important for:
blinking, wound healing, tear production
148
Corneal transplants are doable. If they fail, Keratoprosthesis can be used. This needs..
life-long antibiotics.
| meds to control inflammation and glaucoma.
149
corneal disease can arise from:
epithelia - limbal deficiency
stroma - dystrophy
endothelia - bullous keratopathy
150
Limbal cells have a stem cell niche which produce...
post-mitotic wing cell layer
| terminally differentiated cells - squamous layer
151
Limbal stem cell deficiency can cause:
aniridia, sclerocornea, conjunctiva overgrowth, ocular burns
152
Ocular surface can be restored in ocular burn patients through..
limbal epithelial stem cell transplantation
153
Corneal stem cell transplant used in Holoclar. What is seen?
Stable corneal surface.
little/no ingrown blood vessels.
reduction in pain and inflammation.
vision improvements.
154
Stromal replacements need to be:
acellular.
| promote repopulation
155
Biomaterials used in stromal replacement:
human collagen cell-free implants - this is endogenous, repopulates nerve and stromal cells. Not great improvement of visual acuity.
156
Challenges in treating corneal diseases:
need to recreate epithelium - this needs constant replacement, needs to maintain integrity and have transparency.
recreating stroma - needs transparency and high tensile strength.
Re-innervation is limited - use growth factors?
157
Corneal endothelium does not regenerate in humans. In culture they show...
limited proliferative ability. Should be derived from PSCs instead
158
Peripheral nerve injuries are mainly caused by:
car accidents
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Axons are enclosed by ... Groups of axons are bound together by ... and fascicles are bound by ...
Axons surrounded by endoneurium.
Groups bound by perineurium to form fascicles.
Fascicles joined by epineurium.
160
3 types of peripheral nerve injury:
Elongation
Laceration
Compression
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Neuropraxia is...
no/little structural damage, no loss of nerve continuity.
| symptoms are reversible.
162
Axonotmesis is .... perineurium and epineurium still intact
complete interruption of axon and its myelin sheath. Axon is divided
163
Neurotmesis is complete disconnection of the nerve and surrounding stroma. What is seen?
No spontaneous recovery.
| Weakness and atrophy
164
Wallerian degeneration is ...and includes..
degeneration of the nerve fibre and myelin sheath past the point of the cut - with macrophages (debris), proteases and bands of Bungner
165
In regen of CNS, macrophages infiltrate slowly which delays..
removal of inhibitory myelin
166
In the CNS, reactive astrocytes produce..
glial scars which inhibit regeneration
167
Repair in the CNS is ... whereas repair in PNS is...
CNS=inhibited repair.
PNS=actively promoted repair.
NSs need different strategies
168
Approaches to repair PNS tissue so far:
Surgical reconstruction
Grafts
Nerve conduits
169
Reconstruction of nerves can cause tension which ... If the nerve is stretched by 8%...
reduces blood flow. when nerve is stretched 8%, blood flow reduces to 50%. The nerve is completely ischaemic at 15% stretched.
170
Autologous nerve grafts adv/disadv:
low risk of immune response.
LOF at donor site.
2 surgeries required.
limit to size and type
171
Nerve conduits are guides for regenerating axons. They prevent ... and increase conc of...
Prevent infiltration of scar tissue.
| Increase concentration of intraluminal proteins
172
The nerve conduit connects to proximal and distal nerve stumps. It then fills with...
Conduit fills with plasma.
Fibrin cable forms.
Cells migrate and axon regenerates.
Tissue reforms but notably thinner.
173
Decellularised nerve conduits provide 3D scaffolds with...
clean pathways to allow migration.
Well distrib. for regeneration.
Porosity for plasma to pass through
174
Natural and synthetic materials have been used for nerve conduits including:
Chitosan, collagen, fibrin, fibronectin, keratin.
| PLA, PLGA, PEG, silicone
175
For nerve conduits to be successful the injury gap must not be too large. At longer lengths...
thinning of fibrin cable restricts regeneration
176
To increase the critical gap length of nerve conduits, approaches could be:
ECM components.
Intraluminal support.
Neurotrophic factors.
Cell grafts.
177
ECM components for increasing critical nerve gap are matrices. These include:
Weak viscoelastic hydrogels - high water content.
| Laminin, fibronectin, collagen
178
Intraluminal support to increase critical nerve gap include:
micro-grooved luminal design.
variations in conduit designs.
surface functionalisation.
intraluminal guidance.
179
Functionalisation of nerve guides uses neurotrophic factors eg. NGF and NT3. These will:
support axonal growth.
support prolif and migration of Schwann cells.
increase neuroprotection through intrinsic pathways.
180
Delivery of neurotrophic factors in nerve conduits is done by controlled release methods of:
diffusion-based.
suspension.
affinity-based.
microsphere encapsulation.
181
Schwann cells are criticcal for successful nerve regen as they induce:
Bands of Bungner.
Secretion of NT factors.
Proliferation
182
Nerve gaps larger than 15mm..
cannot be sutured
183
.... is usually used in nerve conduits and it degrades over time.
Bovine type 1 collagen
184
PVA can be used in nerve conduits however it is not ... Fibrosis can occur after 5 years which causes...
PVA is not degradable. Fibrosis causes neuropathic pain - conduit must be removed.
185
Microstereolithography uses ... to turn synthetic materials into solids.
UV light and photocatalytic reactions.
186
Axons wander in conduits. How is this improved?
Lining lumen with PCL fibres at 8 micrometer depth for neuron growth.
187
Nerves have better outgrowth if there is good ... This can be shown by altering..
Needs good cell adherence. Done by altering surface chemistry.
188
Stiffness of conduits is reduced by making them..
more porous
189
Tissues grown in vitro need bioreactors, in vivo they need..
vascularisation
190
Roles of vascularisation:
avoid graft necrosis.
generate thicker tissues.
help graft innervation.
improve graft function.
191
Formations of blood vessels are...
macrovessels - arteries and veins.
microvessels - arterioles and venules.
capillaries
192
Cells need to be located close to capillaries. If islet cells are more than.... they necrose.
100 micrometres
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vasculogenesis is creating a primary capillary plexus from..
mesoderm, hemangioblasts, forming tubes and making plexuses.
194
Important factors of angiogenesis are:
VEGF - vascular endothelial growth factor
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Arteriogenesis can be caused by ...
increasing shear stress - causes endothelial cells to release TGFb, prolif and matrix remodelling.
196
...scaffolds facilitate vascular ingrowth
porous
197
scaffolds are functionalised for vascularisation by:
Controlled growth factor delivery, single or combo - VEGF, PDGF, bFGF.
198
During vasculogenesis, VEGF signals to endothelia which secretes..
MMPs. This creates punctures in the BM, allowing vessel sprouts to form. Matures by recruiting SMC and pericytes.
199
Vascularisation is in a feedback loop with..
hypoxia
200
VEGF is not sufficient to induce maturation. What does this?
PDGF - platelet derived growth factor
201
VEGF and PDGF are used together to form vessels by 2 steps:
1 release VEGF to stimulate growth of immature vessels.
| 2 PDGF from encapsulated microspheres to facilitate maturation
202
Distinct kinetics which mimic natural process and use of multiple angiogenic factors is..
important for engineering artificial vessels
203
Disadv. of strategies facilitating vascular ingrowth:
time consuming - microvessels grow 5 micrometres per hour.
| may not be sufficient to prevent necrosis in 3D constructs.
204
Prevascularisation strategies have been designed to improve vascularisation. In vitro is:
Build a prevascular structure so the prevascular network can anastomise with existing blood vessels - this is faster than new blood vessel formation.
205
In vitro prevascularisation shows endothelial cells can:
spontaneously self-assemble into capillary structures.
| however there are issues with mature cells.
206
In vivo prevascularisation involves:
implanting a scaffold into a well vascularised tissue.
Microvessels ingrow from the host.
Implant is then transferred to the defected site.
207
In vivo prevascularisation can be done by the flap technique:
Scaffold is implanted into a muscle flap.
Entire flap is transferred.
Vascular pedicle of flap is surgically anastomised to host vessels.
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Another in vivo prevascularisation technique is AV looping:
Use a vein to form a shunt loop between artery and vein.
This leads to spontaneous vessel sprouting.
Loop is placed in a protective chamber then transferred.
209
In AV loop technique, tissue is not embedded in..
surrounding muscle tissue
210
Considerations of vascularisation strategies:
Scale up
Cost
Minimal invasiveness
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TE constructs have .. and ... interactions with the body. Causes .. and .. responses.
Local and systemic interactions.
| Inflammatory and immune responses
212
Biomaterials effect processes of:
wound healing.
infection.
toxicity.
tumourigenicity.
213
The body's effects on biomaterials are:
enzymatic degradation.
calcification.
abrasion.
corrosion.
214
Tissues respond to implants by... This involves:
fibrous encapsulation. Involves abundant deposition of ECM and isolation of biomaterial from local tissue
215
Implant infections such as Staphlococci occur because bacterial develop..
biofilms. - these are resistant to antibiotics and host defence
216
Biofilms allow bacteria to embed themselves in the..
matrix
217
Floating bacteria compete with cells and proteins to make interactions with...
biomaterial surface
218
Using biomaterials with non-fouling surfaces can inhibit..
bacterial colonisation
219
Bacterial colonisation could also be prevented by..
using bacteria-repelling proteins
220
Byproducts of physical and chemical wear can enter the bloodstream eg...
metal on metal hip replacements release cobalt and chromium in the blood.
221
A way to avoid immune response is by immunoisolation. What is this?
Uses selectively permeable membrane to enclose biomaterials in - differ in size
222
Immunoisolation has been done with..
stem cell derived islet cell therapies
